Frank m



(No Model.)

F. M. STEVENS.

BALANED SLIDE VALVE.

Patented June '23, 1885.

By his Attorneys,

N. PETERS, Fhuloumngnphar, wanhingun. D. C,

:UNITED STATES PATENT OFFICE.,

FRANK M. STEVENS, OF NEW YORK, N. Y., ASSIGNOB TO THE STEVENS LOCOMOTIYE AND MACHINE COMPANY.

BAL'ANCIED SLIDE-VALVE.

SPECIFICATION forming part of Letters Patent No.320,599, dated June 23, 1885.

Application (iled July 10, 1884.

T0 all whom, it may concern.:

Be it known that I, FRANK M. STEVENS, a citizen of the United States, and a resident of the city, county, and State of New York, have invented certain Improvements in Balanced Slide-Valves, of which the following is a speciication.

My invention relates to certain improvements in means for balancing 0r partly balancing a slide-valve, which means will be fully hereinafter described.

In the drawings, which serve to illustrate my invention, Figure lis a vertical mid-section of the valve and its chest, the section of the valve being taken on line 1 1 in Fig. 2. Fig. 2 is a side elevation, and Fig. 3 an end elevation, of the valve as a whole. Fig. Llis a plan ofthe valve with the balance-plate removed. Fig. 5 is a cross-section of the valve, taken on line 5 5 in Fig. 2. This view is designed to show the packing-strips and their supportingsprings. Fig. 6 is a plan View of the under side ot' the balance-plate.

LetArepresent the valve-seat, provided with the usual ports, a a a,- B, the steam-chest or valve-chest, provided with a cover, b, the lower face of which is parallel with the face of the valve-seat, and O, the valve-stem, arranged to play through a stuiling-box in the chest B, in the usual way.

D is the body of the valve or valve proper. This is rectangular in form, open at the top, and provided with the usual lap-flanges, c, at its base. In the upper edges of the end and side walls, d, are formed grooves e, which extend from side to side and from vend to end of the body D. Into the grooves e in the side walls are placed side packingstrips, f, and in the grooves e in the end wheels are placed between strips f the end packing-strips,f. These latter cannot move endwise and become displaced, as they are embraced between the strips j, and to prevent the strips f from being displaced endwise I provide each with one or more dowel-pins, g, which loosely engage holes at the bottoms of the grooves e, in which these strips are placed. The packing-strips f f are supported on springs, and preferably on leafsprings, h h., placed in the grooves e in the end walls, as indicated in Fig. 5, where one of these `springs is clearly shown.

(No model.)

E isa balance-plate, which is provided with grooves e' c in its lower face, which correspond exactly with the grooves e in the valve proper, and when this plate is in place, as shown in Figs. l, 2, 3, and 5, the upper edges of the packing-stripsf and f engage the grooves c', as clearly shown. The balanceplate E is made true on its upper face, and this face rests on and plays over the under face of the cap b of the chest B.

Secured in the balance-plate E, or forming a part of the same, is a deliection-platell,

which depends into the hollow of the valve proper, D, and has a concave lower face to form a deiector to receive the impact of the exhaust-steam and deflect it downward toward the exhaust-port.

The steam from the chest has access under the packing-stripsff at the open ends of the grooves in which they rest, and holes 'i i, opening through the walls d into said grooves, may also be provided for the admission of steam. This exterior pressure of steam keeps the packing-strips pressed inward against the inner walls of the grooves in which they rest, thereby insuring a stea1n-tight joint, and it also keeps the balance-plate E pressed up to its seat on the chest-cover b. The surface upon which the steam-pressure is exerted to press the plate E upward is equal to the entire Y under surfaces of the packing-strips and the under surface of that portion of the plate E that is exterior to said packing-strips.' To equalize or counterbalance a portion of this, I cut away or rabbet a portion of the upper bearing-surface of plate E atj, so that steam may have access to a part of said upper surface. The amount of surface thus exposed to the pressure of the steam may be regulated and proportioned at will bythe maker. I prefer to rabbet the upper exterior edge of the wallsclof the valves, as at L, in order to insure free access of the steam to the under side of the margin of cap E. This is the more necessary where the chest-cover b is so low as to press the cap E down very nearly to the wall `d of the valve proper.

The valve-stem may be attached to the valve by means of a Thead on the stem engaging a keeper, Z, on the valve, or in, any good way. The function of the springs 71` is mainly to keep the cap E pressed up to its seat where tliereis no steaiapressure on the valve; but they also insure the steam getting under instead of over the packing-strips.

As the top of the valve proper, D, is open, there is no tendency for the valve to 'lift from the pressure upward ofthe exhaust. This pressure is received by the detlector F.

In order to strengthen the valve, which in some eases is quite long, I usually provide it with ties or bridges mm, one or more, which extend across it from side to side, and are cast in one piece with it, as shown in Fig. 4. The deflector F has cross-slots a a to receive these ties.

Having thus described niy invention, I claiml. A balanced slideval ve eoinprisi ng a valve proper with grooves in its top, to receive packing-strips, the said packingstrips, and a balance-plate having grooves in its lower face to receive the upper edges of said packing strips and mounted on the latter, all constructed and arranged to operate substantially as described and shown.

2. A balanced slide-val ve comprising the opentopped valve proper of rectangular forni, provided with grooves e in the tops ot' its sides, the packingstripsfj, the springs that uphold said strips, and the balance-plate E. provided with grooves e in its lower face, the said packing-strips being fitted into said grooves e and e', substantially as and for the purposes set t'ortlr 3. A balanced slide-valve comprising the valve proper, D, provided with grooves for the packing, the said packing, and the balanceplate E, provided with grooves to receive the packing, and with the pendent deiiector F, substantially as shown, and i'or the purposes set forth.

4. The combination, to forni a balanced slidevalve, ot' the valve proper, D, provided with grooves to receive the packing, the said packing, and the balance-plate E, also provided with grooves to receive the packing, and with rabbetsj at its upper edges, to provide a surface for the steanrpressure to act on, substantially as and li'or the purposes set forth.

5. The coinbination,to form abalanced slidevalve, of the open-topped valve proper, D, provided with straight grooves e to receive the springsh andpacking-strips ff, and with the exterior rabbets, 7c, the said springs and packing-strips, the balance-plate E, provided with groovese, to receive the upper edges oi' the packing-strips, and with rabbets j, and the pendent concave deiiector F, secured to or forming apart of plate E, all constructed and arranged to operate substantially as set forth.

In Witness whereof I have hereunto signed my name in the presence ot' two subscribing witnesses.

FRANK M. STEVENS. 

